/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jena.sparql.syntax.syntaxtransform;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import org.apache.jena.graph.Node;
import org.apache.jena.rdf.model.Literal;
import org.apache.jena.rdf.model.RDFNode;
import org.apache.jena.rdf.model.Resource;
import org.apache.jena.sparql.core.Quad;
import org.apache.jena.sparql.core.Var;
import org.apache.jena.sparql.expr.ExprTransform;
import org.apache.jena.sparql.graph.NodeTransform;
import org.apache.jena.sparql.modify.request.*;
import org.apache.jena.sparql.syntax.Element;
import org.apache.jena.update.Update;
import org.apache.jena.update.UpdateRequest;

/** Support for transformation of update abstract syntax. */ 
public class UpdateTransformOps {
    
    /** Transform an {@link Update} based on a mapping from {@link Var} variable to replacement {@link Node}. */ 
    public static Update transform(Update update, Map<Var, Node> substitutions) {
        ElementTransform eltrans = new ElementTransformSubst(substitutions);
        NodeTransform nodeTransform = new NodeTransformSubst(substitutions);
        ExprTransform exprTrans = new ExprTransformNodeElement(nodeTransform, eltrans);
        return transform(update, eltrans, exprTrans);
    }

    /** Transform an {@link UpdateRequest} based on a mapping from {@link Var} variable to replacement {@link Node}. */ 
    public static UpdateRequest transform(UpdateRequest update, Map<Var, Node> substitutions) {
        ElementTransform eltrans = new ElementTransformSubst(substitutions);
        NodeTransform nodeTransform = new NodeTransformSubst(substitutions);
        ExprTransform exprTrans = new ExprTransformNodeElement(nodeTransform, eltrans);
        return transform(update, eltrans, exprTrans);
    }

    /**
     * Transform an {@link Update} based on a mapping from variable name to replacement
     * {@link RDFNode} (a {@link Resource} (or blank node) or a {@link Literal}).
     */
    public static Update transformUpdate(Update update, Map<String, ? extends RDFNode> substitutions) {
        Map<Var, Node> map = TransformElementLib.convert(substitutions);
        return transform(update, map);
    }

    /**
     * Transform an {@link UpdateRequest} based on a mapping from variable name to replacement
     * {@link RDFNode} (a {@link Resource} (or blank node) or a {@link Literal}).
     */
    public static UpdateRequest transformUpdate(UpdateRequest update, Map<String, ? extends RDFNode> substitutions) {
        Map<Var, Node> map = TransformElementLib.convert(substitutions);
        return transform(update, map);
    }
    
    public static Update transform(Update update, ElementTransform transform, ExprTransform exprTransform) {
        UpdateTransform upParam = new UpdateTransform(transform, exprTransform);
        update.visit(upParam);
        Update update1 = upParam.result;
        return update1;
    }

    public static UpdateRequest transform(UpdateRequest update, ElementTransform transform, ExprTransform exprTransform) {
        UpdateRequest req = new UpdateRequest();
        req.getPrefixMapping().setNsPrefixes(update.getPrefixMapping());
        
        for (Update up : update.getOperations()) {
            up = transform(up, transform, exprTransform);
            req.add(up);
        }

        return req;
    }

    static class UpdateTransform implements UpdateVisitor {
        ElementTransform elTransform;
        ExprTransform    exprTransform;
        Update           result = null;

        public UpdateTransform(ElementTransform transform, ExprTransform exprTransform) {
            this.elTransform = transform;
            this.exprTransform = exprTransform;
        }

        @Override
        public void visit(UpdateDrop update) {
            result = update;
        }

        @Override
        public void visit(UpdateClear update) {
            result = update;
        }

        @Override
        public void visit(UpdateCreate update) {
            result = update;
        }

        @Override
        public void visit(UpdateLoad update) {
            result = update;
        }

        @Override
        public void visit(UpdateAdd update) {
            result = update;
        }

        @Override
        public void visit(UpdateCopy update) {
            result = update;
        }

        @Override
        public void visit(UpdateMove update) {
            result = update;
        }

        @Override
        public void visit(UpdateDataInsert update) {
            result = update;
        }

        @Override
        public void visit(UpdateDataDelete update) {
            result = update;
        }

        @Override
        public void visit(UpdateDeleteWhere update) {
            List<Quad> quads = update.getQuads();
            List<Quad> quads2 = transform(quads);
            if ( quads == quads2 )
                result = update;
            else {
                QuadAcc acc = new QuadAcc();
                addAll(acc, quads2);
                result = new UpdateDeleteWhere(acc);
            }
        }

        @Override
        public void visit(UpdateModify update) {
            Element el = update.getWherePattern();
            Element el2 = ElementTransformer.transform(el, elTransform, exprTransform);

            List<Quad> del = update.getDeleteQuads();
            List<Quad> del1 = transform(del);
            List<Quad> ins = update.getInsertQuads();
            List<Quad> ins1 = transform(ins);

            UpdateModify mod = new UpdateModify();

            addAll(mod.getDeleteAcc(), del1);
            addAll(mod.getInsertAcc(), ins1);
            mod.setElement(el2); 
            result = mod;
        }

        private void addAll(QuadAcc acc, List<Quad> quads) {
            for (Quad q : quads)
                acc.addQuad(q);
        }

        public List<Quad> transform(List<Quad> quads) {
            List<Quad> x = new ArrayList<>();
            boolean changed = false;
            for (Quad q : quads) {
                Quad q1 = transform(q);
                changed = changed || q1 != q;
                x.add(q1);
            }
            if ( changed )
                return x;
            return quads;
        }

        private Quad transform(Quad q) {
            Node g = q.getGraph();
            Node g1 = transform(g);
            Node s = q.getSubject();
            Node s1 = transform(s);
            Node p = q.getPredicate();
            Node p1 = transform(p);
            Node o = q.getObject();
            Node o1 = transform(o);
            if ( g == g1 && s == s1 && p == p1 && o == o1 )
                return q;
            return Quad.create(g1, s1, p1, o1);
        }

        private Node transform(Node n) {
            if ( Var.isVar(n) )
                return TransformElementLib.apply(Var.alloc(n), exprTransform);
            else
                return TransformElementLib.apply(n, exprTransform);
        }
    }

}
